Blade assembly



S. H. FEDAN ET AL BLADE ASSE BLY Dec. 29, 1959 4 Sheets-Sheet 1 FiledJune 25, 1956 INVENTORS .r f m 3 T L 10 Dec. 29, 1959 s. H. FEDAN ETAL2,918,977

' BLADE ASSEMBLY Filed June 25, 1956 4 Sheets-Sheet 2 IN V EN TOILS\SJDA/d. 7' F5 061/ Norma M J. .64 7.

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BLADE ASSEMBLY Filed June 25, 1956 4 SheetsSheet 4 IN V EN TOR-SQSJDA/ZY M F5044 United States Patent F BLADE ASSEMBLY Sidney H. Fedanand Norman J. Ely, Baltimore,'Md., assignors to Koppers Company, Inc., acorporation of Delaware Application June 25, 1956, Serial No. 593,474

"6 Claims. (Cl. 170-159) This invention relates to blade assemblies andmore particularly to blade assemblies for industrial fans and to amethod of making such assemblies.

With the rapid industrial expansion of today, there has been an everincreasing demand for eflicient and adequate heat exchange equipment toaccommodate the waste heat inherent to such expansion. To meet thisdemand, industry has turned to such heat exchange means as the coolingtower and the radiator-type cooler, both of which means are dependentupon the industrial cooling fan.

'These industrial fans have had to be more than just a paddle wheel inorder to move air in an efficient manner without excessive speeds ofrotation and, in the past, some of the earlier models of industrialcooling fans have been similar to the common desk fan or airplane-typepropeller. Today, there are many types of fan blade assemblies as Wellas several well'known'methods of constructing such fan bladeassemblies,including methods wherein laminated wood is carved andcovered by plastic .to form the industrial fan blade, wherein theindustrial fan blade is formed from plastic material itself, and whereinthe industrial fan blade is formed from cast metal. Although thesevarious assemblies and the various methods of manufacturing them havemet some of the fan blade problems of corrosion, strength, fatigue,efliciency, sound level, and balance, none has been able to meet withall of these above-mentioned problems as efliciently as has the presentinvention. 7

The present invention provides a fan blade that is lightweight,resistant to fatigue and corrosion, aerodynamically efficient, and ofhigh strength. In addition, the present invention provides an economicaland eflicient method of manufacturing such a blade in a straightforwardand uncomplicated manner.

Various other features of the present invention will become obvious witha reading of the disclosure set forth hereinafter.

More particularly, the present invention provides a method of making ablade assembly comprising the steps of casting .a quantity of selectedquality lightweight metal in a .mold to form a metallic shank member,extruding a further quantity of selected quality lightweight metal toform a ribbed camber member and a thrust member of a blade section,stamping a selected quality lightweight metal plate to form a tip memberof such blade section, and Welding the cast shank member, the extrudedcamber member, the extruded thrust member, and the stamped membertogether to form a metallic blade assembly. The present invention alsoprovides a blade assembly which includes a retention shank member havingintegral therewith a transverse flange and an anchor-extending from theflange, and a blade section fixed to the shank mem her, the bladesection including a camber member having a ribbed face, a thrust memberincluding a face portion fixed to the camber member in facing relationwith the ribbed face thereof, and a tip member closing the open end ofthe joined camber and thrust members, the camber member having at itsroot end a socket of configuration 2,918,977 Patented Dec. v29.,

identical to theanchor of the shank member to receive the anchor so thatthe sides of the anchor abut against the sides of the socket and theroot end side of the camber member abuts against the side of thetransverse flange of the shank member. Further, the present'inventionprovides interlocking means along the abutting sides to interlock theblade section to the shank member.

It is to be understood that various changes can be made by one skilledin the art in the several steps of the method disclosed herein and inthe several parts of the blade assembly also disclosed herein withoutdeparting from the scope or spirit of this present invention. 1

Referring to the drawings:

Figure 1 is a perspective view of an advantageous embodirnent of thepresent invention, disclosing one face of an assembled blade sectionprior to its assembly with a hub-member;

Figure 2 is an exploded perspective view of the various members whichare joined together to form the blade assembly of Figure 1, this viewshowing the other face of of the assembled blade section and retentionshank member;

Figure 7 is a cross-sectional view taken in a plane passing' throughline VII VII of Figure 6, showing details of a portion of the interlockbetween the assembled camber member of the blade section and theretention shank member;

Figure 8 is a cross-sectional view taken in a plane passing through lineVIII-VIII of Figure 7, showing further details of'the interlock betweenthe assembled camber and retention shank members;

Figure 9 is an enlarged broken plan view of a modified,

assembled blade section and retention shank member, disclosing a furtheradvantageous embodiment of the present invention: I

Figure 10 is a cross-sectional view of the modified assembled bladesection and'retention shank member of Figure 9, taken in a plane passingthrough line X-X of Figure 9. I I

As can be seen in Figure 1 of the drawings, the blade assembly of thepresent invention broadly comprises a retention shank member 6 and bladesection 7. Referring to Figure 2, blade section 7 includes camber member8, thrust member 9 and tip member 11. When the blade is properlyassembly together, as will be described hereinafter, spindle 12 of theshank member is nested in the hub socket 13 of hub 14 and held in placeby clamping bracket 16 fastened to hub 14 by means of tap bolts 17(Figure 1).

In an advantageous embodiment of the invention described hereinafter,the blade sizes can range for fans from approximately 9v feet toapproximately 22 feet in diameter. For blades used in fan models 9 feetthrough 10 feet in diameter, the chord width of the blade can be 10inches. For blades use in fan models 11 feet through 14 feetin'diameter, the chord width can be 12 inches and for blades used in fanmodels 16 feet through 22 feet in diameter, the chord width can be 16inches. In this connection, it is to be noted that when the chord widthis 16 inches, a modified construction of the blade section can beprovided in order to effect an economy in the blade assembly.

Figures 9 and 10 of the drawings and described hereinafter.

Referring to Figures 2-5 of the drawings, it can be seen that shankmember 6 includes the aforementioned "spindle 12,'trans verse flangeportion 18 integral with this spindle, and'anchor portion 19 integralwith and extending from this transverse flange portion. Provided along'the'sides of the transverse flange portion 18 on either side oftheextending anchor 19 are interlock projections 21, these interlockprojections serving to interlock the 'blade section to the shank memberas will be described hereinafter. Referring particularly to Figure ofthe drawings, it 'can be seen that the interlock projections 21 eachhave a reduced head portion 22. This head portion, in turn, is steppeddown or reduced at one side 25 (Figure 3) 'so that the head portion isadapted to engage properly "withchanneled ribs in the camber member ofthe blade T section when the sides of the anchor of the shank member arepositioned to abut against the sides of the socket of the camber member.It also .can be seen that each interlock projection 21 is provided withwells 23. The

wells 23 are adjacent the reduced head portion 22 and on opposite sidesthereof, these Wells serving to receive 'weldin'g material used to fixthe". camber member to the shank member v rn addition to theaforementioned interlockprojections 21, further interlock means ofsimilar construction are provided at the extremity of the anchor 19 ofthe {-shank member. Referring particularly to Figure 3 of the dr'awingsit can be seen that the extremity of the anchor member is provided withspaced ribs 26, 27, and 28 with a, groove 31 interposed between the ribs26 and 27, and

'ag roov'e 32 interposed between the ribs 27 and 28. These ribs andgrooves on the anchor portion are adapted to align with the hereinafterdescribed ribs and grooves of Ithe'camber member of the blade section.As can clearly 'beseen in Figures 3 and 4, at the extremities of eachthe rib members 26, 27, and 28, there is provided'a reduced head portion34, this head portion having adjacent thereto, and on oppositel sidesthereof, wells 36 which are also adapted to receive welding material forfixing the camber member to the shank member; It is to be noted furtherthat the spindle portion of the shank member 6 can be provided, as isknown in the art, with a recess 37 in order. to provide. for properbalance of Shank member 6, in an advantageous embodiment of the. presentinvention can be a permanent mold casting of aluminum alloysuch as thatcommercially designated ,A356,T71 The alloy A356-T71 has a chemical composition of 7.0% silicon and 0.3% magnesium with the balancealuminum andit is a member of the siliconmagnesium family of alloys. By using such'an alloy, it is possible to obtain excellent-casting features incarryjing out the'processjof castingthe shank member in a permanent moldand it is further possible to obtain a shank member of high strength andgood resistance to icorrosion. Inthis connection, it is to be noted thatthis alloy has been found to have a tensile strength of 32,000 p.s.i., ayield strength of 24,000 p.s.i., an elongation of and an endurance limitof 11,000 p.s.i. Furthermore,.the resulting permanent-mold cast shankmember has proven to have higher mechanical properties due to its bettermetallurgical structure than a sand-cast shank 'member and has proven tohavea superior surface finish,

5 and 28.

The ribs serve to add to the desired structural rigidity of the cambermember, ribs 26', 27, and 28 being arranged to align with ribs 26, 27,and 28 respectively of anchor 19 when the blade is assembled.

5 The socket 38 (Figure 2) of the camber member is of a configurationidentical to the anchor 19 of the shank member and serves to receive theanchor when the blade is assembled so that the sides of the anchor abutagainst the sides of the socket and the root-end sides of the 10 cambermember abut against the sides of the transverse flange portion 18 of theshank member. When this occurs, the stepped down portions 25 of thereduced head portions 22 of each of projections 21 interlock into therecesses formed at the root ends of channeled ribs 26 At the same time,the reduced head portions 34 provided on each of the ribs 26, 27, and 28of the anchor interlock into the recesses formed by channeled ribs 26',27', and 28' along the bottom side of the socket 38 in the cambermember. Thus, an interlocking arrangement is effected between the cambermember and the shank member. With such an arrangement, a readypositioning and alignment means is provided for assembling the twomembers together and blade bending .moment is resisted firmly betweenthe shank member and the camber member after such assembly.

thermore, the ribs 26', 27', 28', 41, and .42, which serve to providestructural stiffness and interlock as aforedescribed, and which alsoserve to support the face portion of .the thrust member 9 when it isassembled with the camber member, are more readily and efficientlyformed by such extrusions. a t

In an advantageous embodiment of the invention, the aluminum alloy usedto form a camber member can be -one which is known commercially as6063-T6. The

physical properties of 6063-T6 have been foundto include a tensilestrength of 35,000 p.s.i., a yield strength -of 31,000 p.s.i., anelongation of 12%, and an endurance limit-of 9,500 p.s.i. The chemicalcomposition of this alloy is 0.4% silicon, 0.7% magnesium and thebalance aluminum, this alloy also being a member of the siliconmagnesiumfamily of alloys. With the use of such an alloy for the camber member,the camber has a pleasing surface finish, adequate strength for diversestructural applications, and a good resistance to corrosion.

,. It is to be understood that the thrust member 9 (Fig- .ures -1 and 2)can also be of aluminum extrusion alloy 6063-T6, tothus have the samephysical properties and metallurgical characteristics as describedabove'for the camber section. In an advantageous embodiment of theinvention, the minimum thickness of the camber section extrusion can beapproximately 75 of an inch with solid sections at the leading andtrailing edges of 1% inches and 1% inches, respectively. As for thethrust member, for blades having chord widths from 10 inches through 112inches, thethrust member can be substantially all face portion of inchthickness and can be of substantially the samesize and configuration asthe camber member, ,as shown in the embodiment disclosed in Figure 2 ofthe drawings. ;However,-in instances where blades having chord widths of16 inches aredesired, it is then advantageous that the face portion ofthe thrust member be in creased in thickness to of an inch and that thethrust member be extruded to include, not just the face portion, but" aportion of the camber member aswell, and that the member be'extruded toinclude a portion of the thrust member. With such an arrangement, it isthen possible to extrude both a narrower camber member and a narrowerthrust member, thus obtaining those economies commensurate withextrusion practices for narrow members and, at the same time, obtainingthe wider 16 inch chord width through an interlocking of the twomembers. Referring to Figures 9 and 10, specific details of such aninterlocked camber and thrust member arrangement are disclosed. As canbe seen in Figure 10, camber member 60 of this advantageous embodimentof the invention, which for the most part is like camber member 8 ofFigure 2, is provided with ribs 66, 67, and 68, the ribs 67 and 68 beingof T-shape cross section substantially like the ribs 27' and 28 of thecamber member 8. However, it will be noted that the rib 66 is of anL-shape cross section rather than a T-shape cross section. Thisarrangement facilitates eflicient interlock of the camber and thrustmembers as will be described hereinafter. It also will be noted that aportion of the camber member 60 adjacent the rib 68 is omitted, and itwill be further noted that a portion of the camber member adjacent therib 66 has integral therewith a flat overlap portion 70 which cooperateswith the face portion of thrust member 71, the thrust member 71including, in turn, an overlap portion 75 which cooperates with thecamber member adjacent rib '68. Both the overlap portions 70 and 75 areprovided at their extremities with a hook-like construction 72, thishook-like construction serving to provide effective interlocking andwelding of the camber and thrust members. From the disclosure in Figures9 and 10, it can be seen that both the camber member 60 and the thrustmember 71 have a shorter overall width as a result of the interlockingarrangement, and thus economies of extrusion through shorter widths canbe obtained.

The tip member in an advantageous embodiment of the invention can bestamped from a A; inch thick aluminum alloy plate which can be of analloy designated commercially as 606l-T6.

In assemblying the several above-described parts of the blade assemblyas disclosed in Figures l-8, the camber member 8 and the shank member 6are brought together with the anchor 19 of the shank member engaging inthe socket 38 of the camber member and the interlocking means on theshank member, namely reduced portions 25 and 34, properly nesting in therecesses provided by the channeled ribs 26', 27', and 28 of the cambermember. The two members are then welded together by continuous welds ofspecial alloy wire, which can be an alloy commercially designated 5154.A welding process known as the Consumable Electrode Process of weldinghas been found desirable for welding the two members together, thisprocess utilizing an argon inert gas envelope to prevent oxidation. Sucha process serves further to eliminate corrosion from flux entrapment,and its rapid application reduces the heat effect on adjacent metal.

Once the camber member and shank member are welded together, the thrustmember 9 is fastened to the ribbed face of the camber member and iswelded by a process like that above-described to the camber member alongthe sides of the outer ribs 41 and 42. In this connection, it is to benoted that the thrust member and the camber member are not joinedtogether along the internal ribs 26, 27, and 28'. This serves to preventany internal stressing at such areas. It also is to be noted that a well50 is provided at the base of anchor 19 and that wells 51 and 52 areprovided along ribs 41 and 42 respectively, these wells serving toreceive welding material used to fix the thrust member to the assembledcamber and shank members.

It is to be understood that the camber member 60 of Figures 9 and 10, issubstantially like the camber member 8 at its root section and isassembled to a shank member 6 in substantially the same manner. In this'6 connection, it will be obvious from the above description that thethrust member71 is interlocked with camber member 60 and welded alongthe hook-like extremities 72, the hook-like arrangement serving toreceive the welding material used to fix the members together.

With the three parts of the assembly welded together, the tip plate isthen welded advantageously by the continuous weld process at theextremity of the joined camber and thrust members opposite the shankmember in order to close the open end formed by the camber and thrustmembers. It is to be noted that vent holes are not required in theassembly described since the continuous weld process allows no entranceof moisture.

As a further step in preventing corrosion which so frequently arises inthe corrosive atmosphere of industrial plants, the blade assembliesdescribed above can be provided with a special surface preparationtreatment and then covered with at least one coat of corrosion resistantpaint. Such a surface preparation treatment can include dipping at leastthe blade section of the assembly in a multi-stage acid-etch bath toform a protective surface on the aluminum and to provide an improvedsurface for adhesion of corrosion resistant paint coating. 'It is to benoted that the aforementioned multi-stage acidetch dip bath can be ofthe commercially known Al'odine 100, which is a protective coating foraluminum developed by the American Chemical Paint Company of Ambler,Pennsylvania. This bath serves to form a thin, tough, durable,non-metallic amorphous phosphate surface on aluminum. The coating ofcorrosion resistant paint can then be put on over the top of thealuminum, advantageously in two coats. The paint can be of the catalyzedepoxy type which has great resistivity to corrosive mediums and alsoexcellent adhesive properties. In this connection, it is to beunderstood that other similar type bath solutions and paint coatings canalso be used to prevent corrosion.

In order to prevent galvanic attack when a blade assembly of aluminumand a hub of the dissimilar metal, iron, are united in wet or moistatmospheres, it has been found desirable to insulate these twodissimilar materials from one another. To accomplish this, the aluminumretention shank member 6 can also be treated with an Alodine surface anda two coat corrosion resistive paint, and the area of the hub wherecontact is made can be treated with a rust inhibitive coating such asParko Lubrite over which a coat of aluminum metal paint can be applied.In this connection, it is to be understood that other similar typesolutions and paint coatings can also be used to prevent galvanicattack.

By carrying out the process above-described and by forming a bladeassembly in a manner as also described above, it is possible to providean industrial fan blade assembly that is lightweight, that is easilyformed, that is resistant to fatigue and corrosion, and that iseconomically fabricated and assembled, thus providing an excellentanswer to the ever increasing problems of waste heat in our expandingindustrial economy.

The invention claimed is:

1. A blade assembly comprising a unitary retention shank member, saidshank member being formed with a transverse flange and an anchorprojecting from said flange intermediate the ends thereof, a bladesection fixed to said flange member, said blade section including aunitary camber member having transversely spaced longitudinallyextending edges terminating at their root ends at the ends of saidflange, a socket formed in said camber member intermediate said edges,said socket being shaped complementary to said anchor to receive inabutting relation said anchor so that the root end side of said cambermember abuts against the side of said transverse flange, and means alongsaid abutting sides to interlock said blade section to said shankmember.

2. A blade assembly comprising a unitary retention shank member, saidshank member being formed with a transverse flange and an anchorprojecting from said flange intermediate the ends thereof, a bladesection fixed to said flange member, said blade section including aunitary camber member having transversely spaced longitudinallyextending edges terminating at the ends of said flange, a socket formedin said camber member intermediate said edges, said socket being shapedcomplementary to said anchor to receive in abutting relation said anchorso that the root end side of said camber member abuts against the sideof said transverse flange, and complementary means formed along saidabutting sides of said flange and said shank to interlock said bladesection to said shank member.

3. A blade assembly comprising a unitary retention shank member, saidshank member being formed with atransverse flange and an anchorprojecting from said flange intermediate the ends thereof, a bladesection fixed to said flange member, said blade section including aunitary camber member having transversely spaced longitudinallyextending edges terminating at one end and having at least a portion ofone face thereof formed with .a plurality of spaced ribs at the ends ofsaid flange, a socket formed in said camber member intermediate said.edges, said socket being shaped complementary to said anchor to receivein abutting relation said anchor so that the root end side of saidcamber member abuts against the side of said transverse flange, andmeans provided" alongsaid'abutting sides of said flange and said shankcoacting with said ribs to interlocksaid blade sectionto said shankmember.

4. The invention as defined in claim 3 in which said blade assemblyincludes a thrust member fixed to said one camber faceand overlies saidribbed portion.

'5. The invention as defined in claim 3 in which said ribs extendcoextensively with said camber member edges.

6. The invention as defined in claim 5 in which said blade assemblyincludes a thrust member fixed to said one camber face and overlies saidribbed portion and in which a member is fixed to the tip end of theblade to said thrust member and said camber member.

References Cited in the file of this patent UNITED STATES PATENTS1,000,602 Jacobs Aug. 15, 1911 1,456,512 .Muller May 29, 1923 1,457,844Leitner June 5, 1923 1,473,121 Nelson Nov. 6, 1923 1,516,556 WilkinsonNov. 25, 1924 2,259,247 Dornier Oct. 14, 1941 2,430,854 Berliner Nov.18, 1947 2,454,200 Perkins Nov. 16, 1948 2,535,917 Gruetjen Dec. 26,1950 2,786,538 Blackburn et a1 Mar. 26, 1957

